Feasibility and sludge analysis of electrocoagulation process for Direct Violet-35 dye remediation

Abstract

The present study investigates Direct Violet-35 (DV-35) remediation using electrocoagulation process. DV-35 which is an industrial azo dye, after release significantly affects the visual appearance of water bodies and hinders the process of photosynthesis affecting plant growth. Perturbing the food chain, it promotes toxicity, mutagenicity, and carcinogenicity. Therefore, dye remediation is essential before discharge into water streams. To determine the effectiveness of the electrocoagulation process for DV-35 dye remediation, and understand the influence of parameters like current density, inter-electrode spacing, concentration of electrolyte, pH, agitation speed, and initial dye concentration, a detailed study was carried out. Maximum removal efficiency (>98 %) was achieved in 16 min at 263.15 A/m2 current density and pH 7.2 for DV-35 concentration of 50 to 500 mg/L. Further, optimized parameters were applied to real textile effluent achieving 99.8 % efficiency. EC mechanism was corroborated by Sips isotherm matching adequately with experimental results. The findings also demonstrated a heterogeneous surface of the produced EC flocs. Pseudo-second-order was obtained with a low operating cost of 0.0018 US $/m3. The DV-35 removal and functional groups were confirmed by UV/VIS and Fourier transforms infrared spectroscopy analysis. The sludge was examined by X-ray Diffraction and Scanning Electron Microscope revealing Crystalline aluminum oxides i.e. bayerite (Al(OH)3) and diaspore (AlO(OH)). The conclusion of the results revealed EC to be an effective and economical technique for DV-35 remediation from textile wastewater.